1. Field of the Invention
The present invention relates to a semiconductor device. More particularly, the present invention relates to a non-volatile memory, and a manufacturing method and an operating method thereof.
2. Description of Related Art
Since EEPROM among non-volatile memories can be used to store, read, or erase the data several times, and data stored in EEPROM will not be lost even if the power is cut off, EEPROM has become a popular memory device and is widely used in personal computers and electronic apparatuses.
The typical EEPROM employs a doped poly-silicon material for fabricating the floating gate and control gate. Moreover, in order to prevent the problem of data error due to over-erase phenomenon when the typical EEPROM erases, a select gate made of doped poly-silicon is further disposed on the sidewalls of the control gate and the floating gate and above the substrate, i.e. a select transistor is disposed on the side of the memory unit.
However, such memory usually needs an isolation structure to prevent the memory cells from communicating with each other. And a single memory cell of such memory can only store one bit of data, thus it is quite detrimental to the device integrity.
Furthermore, as three kinds of gates (floating gate, control gate and select gate) are disposed, extra lithography steps are required making the fabrication process more complicated, and increasing the fabrication cost, and also increasing the fabrication time. Additionally, the process yield is decreased, and the stability and the reliability of the memory are reduced due to the additional process steps.